1. Field of the Invention
This invention relates to a lock out assembly for electrical control devices, such as circuit breaker switches with external operating handles and particularly, to a lock out assembly by which the handle can be locked in one predetermined operating position aided by a conventional padlock, or with a conventional hasp and padlock.
2. Prior Art
There are numerous instances when it becomes necessary to assure that one or more circuit breakers in a panel board be inoperable, while at the same time the remaining circuit breakers be freely operable for both the open and closed positions. This is accomplished by providing individual circuit breakers with some type of lock out device. The lock out device is positioned to block movement of the circuit breaker handle in either its "on" or "off" position. It is required that the lock out device be secured in such a manner that an unauthorized person cannot readily remove or otherwise tamper with the lock out device to defeat its intended purpose.
Many of the prior art implements provide a lock out device for a circuit breaker used in field installations. However, lock out devices for field installation require removal of the panel board front cover plate for installation of the lock out device on the desired circuit breakers. Other prior art implements comprise lock out devices which fit over or around the circuit breaker handle, but can be pried loose from the handle with little effort, defeating the intended purpose of the lock out device. Still other lock out implements are not universally adaptable insofar as they require special grooves or inserts in the circuit breaker.
U.S. Pat. No. 3,291,924 discloses a locking device for a circuit breaker handle including employment of a padlock. However, the locking device depends upon biting edge 25 to prevent the device from being pried loose from the handle. Because most handles are tapered, the outer most portion of the handle is narrower than the base portion of the handle and the locking device can easily be pried loose off even when "locked" in position.
U.S. Pat. No. 3,376,400 discloses a locking device for a circuit breaker handle which also includes a padlock. However, the locking device possesses tongues 33 and 35 that insert into the circuit breaker. This requires the circuit breaker to have a specific shape which defeats universal application of the device.
U.S. Pat. No. 3,678,228 also discloses a locking device for a circuit breaker handle, including a padlock. The locking device is similar in nature to U.S. Pat. No. 3,376,400 described above because the device comprises two tongues which only fit specific shaped circuit breakers.
U.S. Pat. No. 4,160,137 shows a circuit breaker with a locking device for the handle, including a padlock. The locking device is a two part device, each part having one curved portion. One portion of the device is slipped over the circuit breaker handle while the other portion is fastened to the first portion by means of screws. The locking device fits a specific shaped circuit breaker having undercut grooves adapted to receive the curved portions of the locking device. Again, the device is limited to specific shaped circuit breakers.
U.S. Pat. No. 4,260,861 shows a circuit breaker with a locking device including a padlock. The locking device comprises a three piece unit which is only adaptable to a specific type circuit breaker. Two hook like projections secure the locking device to corresponding indents of the circuit breaker.
None of the above addressed prior art implements are acceptable because: (1) either they do not work since they can be pried loose, or; (2) they are not universally adapted to the conventional circuit breaker. Moreover, some of the above addressed prior art implements are multi-piece items which require assembly time. Also, further delays result if any pieces become lost. Thus, a need exists for a one piece lock out assembly, universally adaptable for conventional circuit breakers, which cannot be pried loose once locked into position.